originally denoted the "purple-fish," then, "purple dye" (extracted from certain shell fish): hence, "a purple garment," Mar 15:17, Mar 15:20, Luk 16:19, Rev 18:12.
"purple, a reddish purple," is used of the robe put in mockery on Christ, Joh 19:2, Joh 19:5; in Rev 17:4 (in the best texts; some have No. 1); Rev 18:16, as a noun (with himation, "a garment," understood).